Aircraft: SMALL AIRCRAFT; LOW WING; 1 ENG; FIXED GEAR
Phase of flight: Descent
Anomaly: ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy

I was watching a trainee in the Local Control position when ground/flight data/clearance delivery passed inbound information from ZZZ ARTCC of Aircraft X two miles south east of the airport for a visual approach to Runway XX. This was an extremely late inbound as our LOA reads center will inbound aircraft at least 10 miles out. We had several VFR aircraft in the rectangular pattern to Runway XX with aircraft on final to Runway XX with almost no time to build a hole. We coordinated with center to not descend Aircraft X below 4;000 and requested control which he was at 5;000. Center descended Aircraft X to 4;000 and cleared the aircraft for the visual approach to Runway XX and switched the aircraft to us. We had to move at least two aircraft out of Aircraft X way with little to no notice to accommodate the IFR arrival. Because we were advertising Runway XX/XY in use and Aircraft X was so high (5;000); I thought since we didn't get an inbound that center was vectoring the aircraft around potentially for spacing. Never did I think Aircraft X was going to be cleared a visual approach to Runway XX at the altitude the aircraft was at. Common practice is center inbound aircraft outside of 10 miles for the IFR approach and descends them to 3;000 feet before switching them to us. This created a dangerous situation with very little time to react or plan; especially with a trainee who was on day 4 of re-entering training after six months plus of not working local due to COVID and me not training anyone for just as long if not longer due to COVID.Follow the LOA between ZZZ ARTCC and ZZZ Tower. I was training on local; which I had not worked local in about 6 months due to the COVID pandemic; it was my fourth day back into training. I had numerous aircraft in the local pattern and on final for Runway XX. ZZZ Center called flight data (FD) / Ground Control (GC) and in bounded Aircraft X; who was two miles south east of the field at five thousand feet. I coordinated with FD/GC and ZZZ Center to stop Aircraft X's descent at four thousand because I had several VFR aircraft in the pattern and lining up on final. Shortly thereafter Aircraft X calls me about one to two miles northeast of the field saying he is on a visual approach to Runway XX. I asked Aircraft X how long he would need to continue north before he would turn base in which he told me about another mile and then he would turn his base. I acknowledged him and told him to report turning base. I then started moving aircraft out of the way and sequencing aircraft behind him in order to make it work. I had very little time to plan and build a gap for Aircraft X to fit into. Per our LOA with ZZZ Center; ZZZ Center is supposed to inbound aircraft at least 10 miles out. This aircraft was not inbounded until two miles southeast of the field. Being that I had not got a position on Aircraft X when I noticed him so close to the airport on the STARS; I was under the impression that center was vectoring the aircraft for an RNAV XX approach only to find out last minute that the aircraft was going to be doing a visual approach to XX and then I was not given any time to build a gap to fit the aircraft into.In accordance with the LOA between ZZZ Tower and ZZZ Center; the Center is supposed to call with a position on inbound aircraft with a type of approach to expect. My recommendation is for center to follow the LOA and inbound the aircraft sooner; allowing tower time to build gaps for IFR aircraft. Tower Instructor and Developmental reported overlying Center not complying with the two facilities' LOA.